The present invention relates to a spray nozzle and more particularly to a spray nozzle, which produces a uniform spray distribution in a wide-angled, conical area, for instance in a gas/liquid mixing system, which is used in spray-cooling of high-temperature objects such as heated steel or the like.
To cool the high-temperature objects such as heated steel or the like in the course of a manufacturing process, a one-medium nozzle for spraying only liquid therethrough is conventionally used to cool the steel. This one-medium nozzle causes surface cracks in the heated steel due to the local excessive cooling conditions. Cracking should be avoided as the continuous steel casting method is developed to produce steel at high speed. To prevent the surface cracking of the steel and to shorten the manufacturing time, it is required to spread a gas/liquid mixed spray, with equal spray amount and equal liquid-droplet size, across a wide range on the surfaces of the steel. This can be accomplished with a double medium nozzle for passing two kinds of gas and liquid therethrough for the spraying operation, instead of the one-medium nozzle.
Conventionally the two-medium nozzle as described hereinabove was not satisfactory in providing the uniformity of the liquid flow distribution, the size variation of the liquid droplets, the expanded area of the spray in all directions and so on. To cope with the problems as described so far, there has conventionally been employed a double medium nozzle for a uniform spraying operation in a wide angled conical area with, as shown in FIGS. 1 to 5, but such a nozzle had disadvantages in that the uniformity of the liquid flow distribution was unstable, the widthwise expansion of the spray could not be made too large, and particle size of the liquid droplets became uneven.
More specifically, as shown in FIGS. 1 through 5, such a nozzle is made circular or oval, pseudo-oval in shape at the tip end 2a of a flow hole 2 axially formed in the nozzle main body 1, and is provided with a pair of V-shaped cuts 4, 4. Each cut 4 in the body 1, when viewed from the outside as shown in FIG. 3, forms groove of V-shape which faces the opposite cut 4 along the center line of tip end 2a. The V-shape grooves connect with the circular tip end of the hole to form a discharge slot 3. When a gas and water mixed fluid is fed into the flow hole 2 of the nozzle with such a shape as shown in FIGS. 1 to 5, gas "a" is depressed towards opposite sides of the flow hole as the tip end becomes smaller in diameter, and the liquid "w" concentrates in the central portion of the flow hole, because the liquid is non-compressive while the gas is compressive. Accordingly, the gas/liquid spray jetted from the discharge slot 3 produces fine droplets only along both sides of the expansion area, while the central portion of the area has almost liquid only, which becomes liquid droplets of rough particle sizes, resulting in that the width of the spray in the central portion is not spread in a larger area.